Though still growing faster than general inflation and workers' wages, group health care costs rose a modest 3.8% in 2015 to an average of $11,635 per employee, according to a Mercer L.L.C. survey released this month. It is the third straight year that overall health costs have increased less than 4.0%.

Large employers' costs showed a higher dollar cost but a smaller percentage increase compared with those of small employers (see chart, page 23).

To limit cost increases, employers have gotten creative.

They “have made a concerted effort to add programs that help people either improve their health status or, at a minimum, maintain it,” said Tracy Watts, Mercer's senior partner and national leader of health reform in Washington. “While we have seen people moving into plans that require more cost-shifting, there are many more tools available today to help people take care of themselves and to help them shop more effectively for the care that they need.”

Helping to stem health care cost growth, experts say, is the increasing enrollment in high-deductible consumer-directed health plans, which rose to 25% of all health plan types this year compared with 23% last year.

That shift toward consumer-directed plans is “definitely having a dampening impact on the trend,” in part because they cost so much less, said Beth Umland, Mercer's New York-based director of research for health and benefits.

Tamarac, Florida-based City Furniture Inc., which saw a 3.5% increase in group health costs this year, has offered a health reimbursement arrangement plan for years. Now 80% of its 1,300 employees are enrolled, said Janet Wincko, the retailer's vice president of human resources.

To manage rising health plan costs, City Furniture concentrates on helping workers stretch their HRA dollars further and uses a free on-site medical clinic to do so.

“Most of our employees rely on our clinic,” Ms. Wincko said. “When I talk to our nurse practitioner who runs the clinic, her phone can ring all day long, and it's people calling her from locations all across the company.”

Such “care extenders” can have a “significant impact because they have a lower cost of care and are good front lines to directing people to the right kind of care and keeping them out of the emergency room,” said Sandy Ageloff, U.S. West leader of Towers Watson & Co.'s health and group benefits practice in Los Angeles.

As HDHP usage grows, sources say they are most effective when paired with tools to help employees navigate the health care system without draining their savings.

“We are entering consumerism 2.0,” Ms. Umland said, as employers offer more tools such as those to compare costs, and care options that include telemedicine.

For some employers, the focus remains on wellness.

“Ultimately, health costs are going to be lower if your employees are healthier,” said Mike Morrow, Denver-based senior vice president at Aon Hewitt. Though improvements are not immediate, “employers who are investing in long-term programs that help build good habits for their employees are going to have lower costs down the road.”

Cost increases for pharmaceuticals are growing faster than for medical costs, so some employers are putting their focus there to manage spending, Ms. Ageloff said.

“Pharmacy is the component of employee benefit plans that has the highest rate of increase right now,” Ms. Ageloff said of drug costs that today can account for at least 20% to 25% of employers' total medical spending versus the historical 15%.

While health care costs increased about 6% this year at Chicago-based public relations firm Edelman Inc., prescription drug costs jumped more than 15%, said Laura Pietraszek, the company's executive vice president of U.S. benefits.

“We've tended to be a little more flexible with our drug plan, where now we actually need to put those drug management programs in place,” she said, referring to prior authorization, step therapy and drug quantity management programs.

But even as employers are learning to better curb health care cost growth, benefits experts caution that a 3.8% increase in overall health care spending still trumps inflation rates and wage growth. According to the U.S. Bureau of Labor Statistics, the overall U.S. consumer price index increased 0.2% for the 12 months ending in October, while the CPI for medical care services rose 3.0%. Wages and salaries increased 2.1% for the 12-month period ending in September, BLS data shows.

The gap between general inflation and medical cost increases, along with stagnant wage growth, means the impact of cost-shifting on employees is greater than in previous years, said Dave Ratcliffe, Washington-based principal at Buck Consultants at Xerox.

“Employees are having to face these very large out-of-pocket amounts and contribution increases in a time that the wages aren't really moving,” he said.